Occurrence of mycotoxins in maize, grass and wheat silage for dairy cattle in the Netherlands

The occurrence of mycotoxins in 140 maize silages, 120 grass silages and 30 wheat silages produced in the Netherlands between 2002 and 2004 was determined using a liquid chromatography coupled with tandem mass spectrometry detection (LC-MS/MS) multi-method. Deoxynivalenol (DON) was detected above the limit of quantification (LOQ) of 250 μg kg⁻¹ in 72% of maize and 10% of wheat silages. Average DON concentrations were 854 and 621 μg kg⁻¹, respectively, and maximum concentrations 3142 and 1165 μg kg⁻¹, respectively. Zearalenone was detected above the LOQ of 25 μg kg⁻¹ in 49% of maize and 6% of grass silages. Average zearalenone concentrations were 174 and 93 μg kg⁻¹, respectively, and maximum concentrations 943 and 308 μg kg⁻¹, respectively. The incidences and average concentrations of DON and zearalenone in maize silage were highest in 2004. The incidence of other mycotoxins was low: fumonisin B1 and 15-acetyl-DON were detected in 1.4 and 5% of maize silages, respectively, and roquefortin C in 0.8% of grass silages. None of the silages contained aflatoxins, ochratoxin A, T2-toxin, HT2-toxin, sterigmatocystin, diacetoxyscirpenol, fusarenon-X, ergotamine, penicillinic acid, or mycophenolic acid. This study demonstrates that maize silage is an important source of DON and zearalenone in the diet of dairy cattle. Since the carryover of these mycotoxins into milk is negligible, their occurrence in feed is not considered to be of significant concern with respect to the safety of dairy products for consumers. Potential implications for animal health are discussed.